The Internet has become a worldwide packet switched network for communicating not just data, such as email and pictures, but also for providing real-time bi-directional voice communications. The Internet includes a worldwide web (WWW) of client-server based facilities on which Web pages and files can reside, as well as clients (Web browsers) that can interface users with the client-server facilities. The topology of the WWW can be described as a network of networks, with providers of network service called Network Service Providers. Servers that provide application-layer services may be described as Application Service Providers. Sometimes a single service provider does both functions within a single business.
In recent years, broadband access technologies have facilitated the communication of voice, video, and data over the Internet and other public and private packet switched networks. Because broadband technologies are typically deployed by a single transport service provider, like a Regional Bell Operating Company (RBOC), their packet switched networks are often shared by many network service providers and application service providers.
Service providers can offer services that range from Internet access and virtual private network access to Voice over IP, Video on Demand, and Gaming. Because such services can have vastly different network resource requirements, some service providers can offer varying levels of Quality of Service (QoS) to subscribers. For example, service providers may allow subscribers to mark their packet communications with a requested QoS level. Such markings may be made by consumer equipment that the subscriber uses to interface to a packet switched network. The packet switched network may then, based on the requested QoS level and its presently available resources, vary the communication bandwidth and priority that it uses to communicate that subscriber's packet communications.